Modern encryption methods are being increasingly employed in information processing and telecommunication engineering. However, the use of encryption methods and corresponding devices is persistently impeded by the below-described problems and factors, although mass proliferation, particularly in the multimedia sector and in the field of information processing, calls for a very high standard of security:                The encryption of broad-band signals requires the installation of costly crypto-hardware in personal computers and terminals. The currently available low-cost crypto-chipcards operate only at a low throughput rate of significantly less than 100 kbit/s.        Encryption methods are often protected by property rights and not internationally standardized, so that no low-cost mass products with integrated crypto-hardware are available.        For reasons of cost, crypto-hardware for broad-band encryption frequently employs just one encryption method. Consequently, the personal computers and other terminals equipped with one of these methods are not able to support any number of encryption methods. This results in a great restriction in the compatibility of the indicated devices.        
Crypto-hardware is subject to strict international trade restrictions, with the result that the export, for example, of encryption terminals is very greatly restricted, which is why the use of such devices is very greatly limited and the prices for these devices are very high.
The book by Alfred Beutelspacher: “Kryptologie”, Vieweg Verlag, 1993, describes and presents encryption methods such as the Vernam cipher. In addition, encryption methods such as the RSA method are described in ITU/CCITT Recommendations X.509 and in CACM Communications of the ACM, Vol. 21, No. 2. pp. 120-126, 1978.